Technical Field
The present invention relates to an active capacitive stylus, a sensor controller, a system including an active capacitive stylus and a sensor controller, and a method executed by an active capacitive stylus, a sensor controller and a system. In particular, the present invention relates to an active capacitive stylus, a sensor controller and a system including them, which are suitable where one or more active capacitive styluses are operated to repeatedly move into and out of a detection range of sensor electrodes and methods executed by the active capacitive stylus, the sensor controller and the system.
Description of the Related Art
Styluses of various types having a pen shape have become available for use as an inputting device, for handwritten input on a panel of an electronic apparatus. A stylus called an active capacitive stylus includes an oscillation circuit, which sends out a frequency signal to cause an electrode provided near a tip end of the stylus to generate a variation of an electric field (alternating electric field) at a pointed position near the tip end of the stylus. A sensor provided in the electronic apparatus uses a group of electrodes disposed in a matrix form, to detect a variation of the charge amount induced in the electrode group by the variation of the electric field, to thereby detect a signal from the stylus. The position pointed by the stylus is derived based on the position of the electrode at which the signal is detected, the level of the detected signal, and so forth.
Among active capacitive styluses, some styluses can transmit information to a sensor controller by modulating a signal supplied from the oscillation circuit with information, such as pen pressure and a unique pen identification (ID).
An electronic pen disclosed in PCT Patent Publication No. WO2015/111159 (hereinafter, referred to as Patent Document 1) is an example of an active capacitive stylus of the type capable of transmitting information. The electronic pen successively transmits a continuous signal CS for position detection, and a signal block SIB including a first modulated signal obtained by modulating the continuous signal CS with partial information, which is obtained by dividing first information (a unique ID or the like associated with the electronic pen), to the position detection apparatus.
FIG. 14A depicts an example of a transmission signal including the continuous signal CS and the signal block SIB. FIG. 14B shows that the first information is transmitted by a plurality of signal blocks SIB. In FIG. 14B, a division number (block number A, B, . . . , n) represents a number of an ID block corresponding to partial information. A microprocessor of a tablet in Patent Document 1 is configured to output position information, which is obtained from the continuous signal CS, and the first information in an associated relationship with each other.
Communication between an active capacitive stylus and a sensor controller is implemented by a local alternating electric field in the proximity (within approximately several millimeters to several tens of millimeters) of a pen tip electrode. Since communication that uses an electric field exhibits large attenuation in signal level depending on the distance, such communication is interrupted every time the stylus is moved away from the sensor of the electronic apparatus. Therefore, unlike wireless communications such as Bluetooth® communications, the stylus-sensor controller communication is not performed continuously.
Further, even if the stylus and the sensor have a proximate positional relationship with each other, the communication speed is rather limited.
Accordingly, it is desirable to minimize communication resources, such as time and frequency resources, needed for the stylus to communicate configuration data indicative of a stylus function or a stylus ID that do not vary depending on an operation state of the stylus to the sensor.
It would be desirable to provide technical support for: (1) a usage form, in which a user repeats a cycle of moving down a certain stylus, moving the stylus horizontally by a certain distance and then moving up the stylus, to thereby repeat the movement cycle into and out of a detection range of one sensor controller, and (2) another usage form, in which the user alternately uses a first stylus and a second stylus, while the first stylus and the second stylus are distinguishable from each other and while reducing the number of times data, which do not vary depending upon an operation state of the stylus (such as a stylus identifier), needs to be communicated from each stylus to the sensor.